Use github actions cache during docker build

.github/workflows/test-frontend.yml

@@ -36,11 +36,13 @@ jobs:
       - uses: actions/checkout@v4
       - name: Set up Docker Buildx
         uses: docker/setup-buildx-action@v3
-      - name: Build and export to Docker
+      - name: Build and save image locally
         uses: docker/build-push-action@v6
         with:
           # context should remain as the git context
           file: packages/frontend-2/Dockerfile
           load: true
           push: false
           outputs: type=docker,dest=/tmp/speckle-frontend-2.tar
+          cache-from: type=gha
+          cache-to: type=gha,mode=max